This invention relates to a method of inhibiting the growth of protista by passing media containing the protista through a magnetic field. The field is of selected intensity and orientation to disrupt the cellular and sub-cellular processes of the protista to the extent that the desired inhibition is achieved. The invention also relates to apparatus for use in the method.
In this specification the term "protista" includes all monera fungi, bacteria, cyanobacteria, protozoa and other unicellular microorganisms. The media to which the method is applicable includes liquids, solids, particulate materials, syrups, emulsions, slurries, sludges, vapors and gases capable of supporting or containing the protista. Milk, fuels, milk products, semen and blood are particularly contemplated.
Protista are usually rapidly multiplying organisms and their presence in various systems is a problem of significant proportion. This is particularly the case with foodstuffs, drinks and medical equipment. Also there is, worldwide, a considerable problem of protistal growth in industrial solutions, including water and hydrocarbon fuels. The infestation of a fuel system decreases the efficiency of the fuel system, occasionally to such a point that a complete breakdown of machinery occurs.
Attempts have been made to control the grow of protista in fuels and water using biocides but the biocides themselves may adversely affect the performance of the fuel. Also biocides do not deal with the problem of accumulation of dead growths. Further, as is disclosed in Japanese patent application No. 62/180792, problems occur in the chemical treatment of water; namely that chemicals render the water unpleasant to taste, and filters such as charcoal filters themselves constitute breeding grounds for protista.
Various types of magnetic devices for treating water and fuels are known and some are disclosed in the following patent specifications: Russian 1313811; U.S. Pat. No. 4,716,024; U.S. Pat. No. 4,519,919; U.S. Pat. No. 4,469,076; U.S. Pat. No. 4,414,951; U.S. Pat. No. 4,538,582; U.S. Pat. No. 4,460,516; U.S. Pat. No. 4,381,754; U.S. Pat. No. 4,428,837; U.S. Pat. No. 3,060,339; U.S. Pat. No. 4,026,805; U.S. Pat. No. 4,372,852; U.S. Pat. No. 4,568,901; NZ 191716; NZ 94971; Swedish 148904; WO84/03539 and WO85/04893. However, none of these discloses a method of inhibiting protista and there is no suggestion that these devices could be used to inhibit protista. These known devices are used to condition fuels to improve fuel efficiency and to remove inorganic impurities from water or fuels.
One attempt to inhibit the growth of bacteria and algae in water using a magnetic field is disclosed in U.S. Pat. No. 4,065,386. Here the water to be treated is passed through a device in which a magnetic field is generated transverse the direction of flow of the water. The device includes a stack of aligned, annular magnets arranged with the axis of the stack perpendicular to the direction of flow of the water. Also suggested is the use of a magnet surrounding a water duct. The device is intended for use in conjunction with swimming pool filters and chlorites.
The device does seem to inhibit algae but is not particularly effective since some chemical treatment of the water is required. Also the patent teaches that the device treats the water, not the algae, to make the water hostile to the algae. Therefore there is no suggestion that the device could be used to inhibit algae in other media or in fact that other organisms could be inhibited.
The applicants' European patent specification 0 268 475 discloses a method of treating protista in distillates by passing the distillate though a magnetic field. Also disclosed are various devices in which the distillate may be treated. The method and devices disclosed in this document have been used successfully in the treatment of distillates. However the applicant has now discovered that the effectiveness of the method and the devices can be improved if the magnetic fields are arranged in a specific manner, magnetic fields of selected strengths are used, and the residence time of the medium in the field is over a specified minimum. Also, at the time of making the earlier application, the applicant believed that the devices treated the distillates, not the protista. Therefore there is no suggestion that the devices could be used to inhibit protista in other media.
Protistal infestation of milk is another problem world-wide. Spoilage of milk through infestation annually causes losses of millions of dollars. Attempts to alleviate the problem by traditional methods such as pasteurisation have not proved completely satisfactory.
Typically, traditional procedures such as pasteurisation are carried out at a central location after collection from the farm or other milk supply source. This causes a delay between milking and treatment during which the untreated milk is at risk of infestation. High costs are associated with the bulk treatment of milk, having regard to capital expenditure and running costs.
Similar problems occur with many other liquids, gases and solids.